On the lush campus of St. Charles Borromeo Seminary, just outside Philadelphia, you'll find dozens of Roman Catholic priests in the making — young men eager to answer the pope's call to serve.

Phil Tran, 18, is one of those men. An immigrant from Vietnam, he just started his first year at the seminary and turned down a big scholarship to study mechanical engineering at Drexel University to pursue what he considers a "call" to the priesthood.

"He humbles himself to the position where he is serving others," Tran said of Pope Francis. "So that being one of his characteristics, I want to embody that."

From his earliest years, Phil always knew that he wanted to become a priest — so much so that his peers would tease him by calling him "Father Phil."

But that wasn't the case for Eric Tamney, 20, who says that as he was growing up, the priesthood was the "furthest thing" from what he wanted.

"I could have the job I always dreamed of in marketing, and I could do all these things," he said. "But it wasn't going to be part of the plan."

Men seeking to become Roman Catholic priests must be unmarried, commit to a life of celibacy and pursue several years of study before they can be ordained. After just a short while at the seminary, some decide that life as a priest isn't for them.

But with Pope Francis' universal appeal and refocusing of the church away from divisive social issues to caring for the poor, more men than ever before are signaling their interest in becoming priests.

After years of scandal and bad publicity over the Catholic Church's handling of sexual abuse by priests, a turnaround has begun in the U.S. Nationwide, nearly 600 priests will be ordained in 2015.

"It's a renewed enthusiasm, a love for the church," said Bishop Timothy Senior, the seminary's rector. "We certainly see it in the seminary in the young men who are here, as they are energized in their desire to continue to discern their call and to prepare to become Catholic priests."

Enrollment at the seminary is up more than 20 percent this year — the largest spike in a decade.

Francis has chided church prelates for living beyond their means and has said priests should aim to be "shepherds living with the smell of sheep," which Senior interprets as returning the priesthood to what it should all be about.

"It's about bringing mercy, bringing God's love," he said. "And we need to continue to do work with them [seminarians] and develop that."

Seminarians prepare for a welcome-back mass at the Immaculate Conception chapel at St. Charles Borromeo Seminary last month.NBC News